Vintage wood windows are single or double hung, wood windows that have a distinctive look, which many people find desirable. However, vintage wood windows generally insulate poorly, and thus can contribute to building energy inefficiency. Moreover, conventional storm windows for vintage wood windows also insulate relatively poorly, typically comprising sashes that are single pane. Moreover, the single pane storm windows are typically not adapted to be opened and closed. When a conventional storm window is installed it is “closed” until it is uninstalled.
Vintage wood windows typically have relatively narrow shelves or tracks into which screens or conventional single pane storm windows can be installed. The narrow receiving shelves are approximately 1.0625 inch (1 1/16″) to 1.1250 inch (1⅛″) wide, and are therefore too narrow for conventional multi-pane, multi-sash storm window assemblies to fit within. While a thicker multi-pane or multi-sash storm window assembly could arguably be placed in a narrow receiving shelf of a vintage wood window, the thicker storm window assembly would project too far beyond the vintage wood window exterior surface, thereby detracting from a traditional appearance. In addition, multi-pane windows tend to be relatively heavy, which makes opening and closing vertically sliding windows difficult.
While installation of counter balance systems would facilitate opening and closing relatively heavy multi-pane windows, a conventional storm window assembly with a counterbalance installed would be even thicker, and would thus project even more beyond the vintage wood window exterior surface. Therefore, in order to preserve a traditional appearance, even brand new prior art storm window assemblies installed in vintage wood windows tend to be relatively poorly insulated assemblies comprising single pane windows.